The present invention concerns a cutter segment for a disc grinder or the like, said grinder consisting of two oppositely placed cutters made up of several cutter segments attached to each other, at least one of the cutters being rotatable, said cutter segments being provided with a rough surface or with teeth and grooves for the grinding of material such as wood chips.
To reduce fibrous material such as wood chips to fibers suitable for paper production, a mechanical disc grinder may be used. This defibration process consists in feeding the chips into a grinder, where the material is passed between two grinding cutters placed oppositely. The cutter surfaces are full of grooves and longish protrusions, i.e. teeth, and at least one of the cutters rotates. In this way the material undergoes a very rough treatment between the cutters and is reduced to fibers.
Prior-art cutters, which for ease of manufacture and installation are composed of several segments, have the drawback that the defibrated material contains undefibrated wood particles or splinters, while part of the fibres are over-ground and destroyed. In big grinders operated at considerable power levels, vaporization of the water contained in the wood produces so much steam that, because of the steam pressure, it is difficult to maintain a constant distance between the grinder cutters, which is important in view of product quality. Moreover, the steam bursting out of the grinder in an uncontrolled manner often involves significant trouble in the supply of material into the grinder.